Many personal communication and productivity devices have both microphones and speakers to receive and playback audio content. Common examples include mobile phones, notebook computers, game machines, and tablet computing devices. Because of size, portability, and power efficiency considerations, the speaker and audio processing components of such devices are often not optimized to produce high quality sound. The speakers are often small single element transducers that are placed behind or within substantial enclosures, and located in suboptimal locations such as the side or rear of a device. To improve the playback experience of these devices, external speakers are often used. Such speakers are typically connected to the mobile device through an audio port via cabling, or over a wireless link, such as a Bluetooth connection, though other similar methods are also possible. These speakers are often relatively small and portable themselves, such as small desktop or bookshelf size speakers, or can they can be on the scale of car stereo or home system speakers. The use of external speakers usually cuts out the operation of any internal speakers present in the device, but can also supplement such internal speakers. To reproduce the broadest range of audio in most listening environments, such external speakers are generally designed and configured to have a flat frequency response and not compensate for any spectral coloration caused by device configuration or application. However, the variety of different types of portable devices and operating conditions during use has added greater challenges to accurate sound reproduction through such devices. The faithful rendering and playback of audio can be a challenge in environments that feature different audio playback scenarios, such as different client devices (e.g., mobile phones, portable or desktop computers, gaming consoles, and so on), as well as audio content (e.g., music, games, dialog, environmental noise, and so on). Furthermore, small portable devices are generally incapable of matching their performance to the acoustics of their environment.
Although certain methods exist to improve sound from speakers connected to devices with microphones, such prior art systems typically rely on using predefined test signals, such as pink or white noise. Such test signals are often used to try to achieve a desired sound profile, and are chosen for specific audio properties, such as containing a large range of frequencies in a short amount of time (e.g., impulses, chirps, swoops, broadband noise), or being robust to time shifting (steady state pink noise) or both. The use of such test signals generally interrupts the user's listening experience by requiring specific dedicated tuning periods in which program content is not played.
What is needed, therefore, is a tuning and calibration system that improves the sound emanating from external speakers used with portable devices that have internal microphones or microphone interfaces. What is further needed is a speaker tuning system that does not always require test signals that interrupt the listening experience.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.